Z32 Engines: VG30DE vs VG30DETT
Every Z32 has a 3.0-litre, 24-valve, twin-cam V6 from Nissan's VG family. The non-turbo cars get the VG30DE; the twin turbo gets the VG30DETT, which adds a turbocharger for each bank, two charge air coolers and a lower compression ratio. The block, bore and stroke are the same, but a lot around them is not.
Side by Side
| VG30DE (non-turbo) | VG30DETT (twin turbo) | |
|---|---|---|
| Displacement | 2,960 cc (180.6 cu in), V6, DOHC, 4 valves per cylinder | |
| Bore × stroke | 87 × 83 mm (3.43 × 3.27 in) | |
| Firing order | 1-2-3-4-5-6 | |
| Compression ratio | 10.5 : 1 | 8.5 : 1 |
| US power | 222 hp at 6,400 rpm | 300 hp at 6,400 rpm (manual), 280 hp (automatic) |
| US torque | 198 lb·ft at 4,800 rpm | 283 lb·ft at 3,600 rpm |
| Japanese rating | 230 PS | 280 PS |
| Compression test (at 300 rpm) | 186 psi standard, 142 psi minimum | 171 psi standard, 128 psi minimum |
| Spark plugs (NGK) | PFR6B-11 standard | PFR5B-11B standard |
| Idle speed | 700 ± 50 (MT), 770 ± 50 (AT in N) | 700 ± 50 (MT), 750 ± 50 (AT in N) |
| Automatic | RE4R01A | RE4R03A |
| Differential | R200V, 4.083 | R230V, 3.692 |
| Rear wheels | 16 × 7.5 | 16 × 8.5 |
On a compression test the cylinders shouldn't differ by more than 14 psi (98 kPa) from each other. Test with the engine warm, all plugs out and the throttle held open.
What the Twin Turbo Adds
- Two turbochargers, one on each bank's exhaust manifold, each feeding its own charge air cooler (intercooler) behind the front bumper. See turbo information.
- Lower compression pistons (8.5 against 10.5) so the engine can take boost.
- Wastegate control: the ECU can lower boost when its knock sensor hears detonation.
- Oil and coolant lines to the turbos, which add heat and more hoses under an already packed hood.
- A heavier drivetrain: stronger automatic, bigger R230 differential, bigger propeller shaft with a CV joint, wider rear wheels and tires.
- Chassis extras on US twin turbos: Super HICAS rear-wheel steering and adjustable (Sport/Touring) shock absorbers.
Shared Traits
- Timing belt: both engines are interference designs, so a broken belt can bend valves. Replace the belt, tensioner and idlers on schedule, and the water pump with them.
- Variable valve timing: both have Nissan's intake cam timing control, worked by solenoids from the ECU.
- Heat: the engine sits low and tight in the bay. Vacuum hoses, coolant hoses under the plenum, injector connectors and wiring all age from heat. See fuel injector problems.
- Crank angle sensor: the same optical sensor on both. See CAS problems.
Changes by Year
- 1993: new, more reliable injectors on non-turbo coupes; the non-turbo ECU moved from 8-bit to 16-bit; the air injection system was dropped; the turbo oil line insulation was improved.
- 1994: new injectors on the convertible.
- 1995: new injectors on the twin turbo, and the twin turbo ECU moved to 16-bit (late in the 1994 model year).
- 1996: OBD-II diagnostics, and the variable cam timing was dropped for emissions. Nissan kept the 300 hp rating.
The year-by-year list is compiled by owners, not from Nissan. Parts can change partway through a model year, so check by build date when ordering.
Sources Used
- Nissan 1994 300ZX service manual: EM section (general specifications, compression), MA section (spark plugs), EC section (idle speed, wastegate control), AT and PD sections. Read the EM section
- Power ratings and year changes: Wikipedia, Nissan 300ZX, and the owners' change list on 300zx-owners.club.
- Japanese ratings: JDM Buy Sell Fairlady Z (Z32) guide.